(1) Field of the Invention
This invention relates to a client-server system, and more specifically to a network which is composed of client apparatuses and server apparatuses, which are connected to the client apparatuses and execute jobs at the request of the client apparatuses.
(2) Description of the Prior Art
As office automation is improved, client server systems have become popular. Client-server systems are networks being composed of interconnected client and server terminals, the client and server terminals being copying machines, facsimile machines, etc. In such client-server systems, it is possible for a client terminal to request a server terminal to execute a job. Such a construction achieves effective use of the terminals in the network.
Japanese Laid-Open Patents 60-123152 and 60-123153, for example, disclose client-server systems being networks composed of a plurality of client apparatuses such as personal computers (hereinafter PCs) and a plurality of server apparatuses such as printers, the client and server apparatuses being connected to each other via dedicated controllers such as switches.
In such conventional client-server systems, the PCs as client apparatuses load in advance programs for monitoring the state of the printers as server apparatuses so that the PCs can display on their displays information on an output-destination printer specified by the operator, the information including the range of the magnification/reduction of character size in printing, printer state, paper size, number of stocked sheets of paper, paper jam detection, etc. Operators of the PCs can request the server apparatuses to execute jobs based on the displayed information.
With such a construction, however, the PCs must load, beforehand, programs respectively suitable for the server apparatuses. Accordingly, it is troublesome for the operators of the PCs to get information on the apparatuses and the functions the apparatuses provide if the server apparatuses are located in remote places or if the network includes a lot of server apparatuses. Accordingly, such a system tends to cause a problem that a function of a server apparatus cannot be used by a client apparatus, even if the server apparatus is connected to the client apparatus in the network, since the function has not been registered. Such a case may be a hindrance for effective use of the network.
It is comparatively easy for the client apparatuses to register a new terminal as a server apparatus as far as the terminal includes only conventional functions. It often happens, however, that a newly developed terminal is connected to the network and the terminal has new functions not supported by conventional terminals. When this happens, the client apparatuses are required to load a new program which can deal with the new functions under a suitable format. Such a program often displays the new functions of the server apparatuses on the screen, enabling the operator to request jobs based on the new format.
On the other hand, the server terminals receive a lot of jobs requested by the client terminals. Therefore, the server terminals are required to manage jobs requested by client terminals. For such management, it is desirable that each job is given an appropriate priority. Japanese Laid-Open Patents 4-233555 discloses a system in which server terminals are connected to client terminals via a dedicated controller (e.g., a switch). The operator manually operates the dedicated controller to determine the priorities of the jobs. The jobs are executed based on the priorities and order of reception.
If the operator, for example, during an execution of a print job, wishes to execute another higher-priority print job under such a construction, the operator is required to manually operates, the dedicated controller or to input an interrupt instruction. The current print job is suspended while the higher-priority print job is executed, and after the interrupting print job is executed, the suspended print job is resumed.
However, such a manual operation of the controller is troublesome, especially when it is hard to grasp the status of the target server terminal since the client terminal is remote from the target server terminal. Furthermore, the above system may be said to be unsuccessful in managing jobs effectively since the operator must wait until the resumed print job is finished or, alternatively, press a switch when the operator wishes, during the execution of the resumed print job, to execute another higher-priority print job immediately.